<template>
  <div>
    <p>请选择你要购买的书籍</p>
    <ul>
      <li v-for="(itms,index) in arr" :key="index">{{itms.name}} <button @click="btn(index)">购买</button></li>
    </ul>
    <table border="1" width="500" cellspacing="0">
      <tr>
        <th>序号</th>
        <th>书名</th>
        <th>单价</th>
        <th>数量</th>
        <th>合计</th>
      </tr>
      <tr v-for="(itms,index) in arr" :key="index">
        <th>{{index + 1}}</th>
        <th>{{itms.name}}</th>
        <th>{{itms.price}}</th>
        <th>{{itms.count}}</th>
        <th>{{itms.price * itms.count}}</th>
      </tr>
    </table>
    <p>总价格为:{{num}} </p>
    
  </div>
</template>

<script>
export default {
  data() {
    return {
      arr: [
        {
          name: "水浒传",
          price: 107,
          count: 0,
        },
        {
          name: "西游记",
          price: 192,
          count: 0,
        },
        {
          name: "三国演义",
          price: 219,
          count: 0,
        },
        {
          name: "红楼梦",
          price: 178,
          count: 0,
        },
      ],
      
    };
  },
  methods:{
    btn(index){
      this.arr[index].count++
    }
  },
  computed:{
    num(){
      const ar = this.arr.reduce((sum,itme) =>{
       return  sum += (itme['price'] * itme['count'])
      },0)
      return ar
    }
  },
};
</script>